Epoxidation of alkyl esters of 12,13-epoxyoleic acids and evaluation of the diepoxides as plasticizers for poly(vinyl chloride)

Methyl, propyl, butyl, isobutyl, hexyl, cyclohexyl, octyl and 2-ethylhexyl esters of 9,10:12,13-diepoxystearic acid were prepared by peracetic acid oxidation of the corresponding esters of 12,13-epoxyoleic acid. Using a 60 mole per cent excess of peracid at 30 C in chloroform as solvent, epoxidation was complete in 5 hr. A small aqueous phase was observed in the reaction mixture which decreases the amount of peracid available for reaction. This is due to the water and H₂O₂ present in the commercial peracetic acid used. Thin-layer and gas chromatographic analysis showed that the diepoxides formed as isomers. These did not react quantitatively with HBr by the Durbetaki method. Isomers of methyl and propyl diepoxy esters were separated by crystallization. The methyl (pure and mixed isomers), isobutyl, 2-ethylhexyl and octyl (all mixed isomers) diepoxy esters were evaluated as plasticizers of poly (vinyl chloride). Delta values showed that these esters have good compatibility. Results are compared with commercial epoxidized soybean oil control. These diepoxy esters show better low temperature properties and have higher migration and volatility values than the control. They are more efficient plasticizers than the control. The liquid isomer of the methyl ester, as well as the 2-ethylhexyl ester, should be useful as primary plasticizers and in combination with other plasticizers as plasticizer stabilizers. E. Utiliz. Res. Dev. Div., ARS, USDA.